This is a Congressionally mandated study to determine whether the children exposed to chloride deficient formula in 1979 may have suffered some long-term effects which may be expressed in delayed motor and mental development or decreased school performance. This project is done through a contractional arrangement with JRB Associates and the active collaboration of the Centers for Disease Control. The initial effort will consist of the identification of children exposed to the chloride deficient formula who were sufficiently ill to require hospitalization in 1979 and who had evidence of hypochloremic metabolic alkalosis. Also during the first year a battery of tests will have to be chosen for the evaluation of these children and a group of control children identified. These children and their control group will be evaluated during the second year. The third year of the study will be devoted to analysis.